This is how you make a floating head in minecraft:

1. make a little 3x3 space so that the zombies dont go out
*fences recomended

2. spawn a lot of mobs that goes on fire
*zombies
*skeletons

3. drop any head
*human head
*skeleton skull
*zombie head
*yuor head :P
*wither skeleton skull
*etc. [if there's any]
*make sure a mob picks up the head and puts it on :P
4. do /set time day and wait till they all burn to death
*the one mob that has the head on must not be burning

5. get invisibility splah potion and hit the mob
*the head itself must not be invisible
*should be floating
*highly recomended:
particals on

6. so if you walk past it ill be staring at you @_@

7. thats it!
*if this doesnt work post it in the comments